Detent-tripping mechanism for socket switches



May 11 1926.

R. D. SMITH DETENT TRIPPING MECHANISM FOR SOCKET S WITCHES Filed Nov. 78,

Patented May 11, 1926.

UNITED RAYMOND D. SMITH, OF SCARSDALE, NEW YORK, ASSIGNOR, BY MESNEASSIGN- MENTS, TO TREMONT PRODUCTS CORPORATION. OF BOSTON,MASSACHUSETTS, A.

CORPORATION OF MASSACHUSETTS.

DETENT-TRIIPPING MECHANISM FOR SOCKET SWITCHES.

Application filed November 8, 1920. Serial No. 422,751.

This invention relates to a detent-tripping arrangement, specificallybut not exclusively for pull socket switches, wherein a common, manuallyactuable means is employed co-operatively with a resilient means and adetent to tension a controlled mechanical element for'movement normallyprevented by said detent and subsequently to release said element fromrestraint by said detent by mechanically tripping the latter.

The broad object of the invention is to provide in a partially automaticapparatus (such as a pull socket switch partially governable by athermostatic detent) having a single, manually actuable element forcontrolling the same (such as a spring restored pull chain), a trippingmechanism whereby when tension is established by one full stroke of saidelement for later causing automatic detent-delayed movement of anoperative part (such as a switch circuit controller) a subsequent manualactuation of said element will operate to tri the detent and releasesaid part immediately to permit its said movement.

The novel principles embodied in my present invention may advantageouslybe applied to delayed cut-offs for pull sockets of the general typedisclosed in my copending application, Serial No. 421,556 filed Nov. 3,1920. The type of switch here employed as the delayed cut-off abovementioned includes a current distributor arranged to be establishedunder tension tending to move the same to break the circuit butpermitted so to move only upon. thermostatically caused retraction of anornn'llly restraining detent, such retraction taking place after asubstantial interval of time such as that required for the thermalenergization of the thermostat by the electric current. In the mostsimple form of the above described switch. however, no means is providedfor manually causing direct and immediate circuit-breaking switch actionif desired but the operator must always wait upon the delayed-actingautomatic switch action above described.

The only means that have heretofore been provided in this connection formanually causing direct and immediate cut-off action independently ofthe thermostatic delayed acting detent has consisted in a co-operativeformation of the engaging portions of the above mentioned currentdistributor and the thermostatically.controlled detent hook, whereby anunusually forceful pull on the switch control chain operates to forcethe detent hook out of engagement with the distributor by excessivethrust of the latter on the intercepting portion of the, former topermit circuit-breaking movement of the distributor. This arrangementdepends in operation upon a proper balancing of co-operative springforces and causes strain and wear upon parts necessarily employed whichare comparatively small and delicate.

Accordingly, in applying my invention to improve the operatingconditions described above, the particular object is to provide atripping device for the. detent hook whereby, preferably, a repetitionof the initial stroke of the pull chain subsequent to the stroke thereofthat places the current distributor under tensioned restraint by saiddetent hook, is operative to retract the detent hook from interceptingengagement with the distributor in a natural, un-- as shown on theaccompanying drawings in which:

F 1g. 1 1s a view of the complete socket switch in elevation, the caslngand certain other parts being partially broken away to show the interiorswitch structure in which is embodied my improved detent tripping 95mechanism.

Fig. 2 is a plan view of the switch mechanism taken partly insection onthe plane 22 in Fig. 1 and showing the relation of parts when the lampcircuit is normally 100 closed.

Fig. 3 is an enlarged fragmentary view in elevation looking in thedirection of arrow 3 in Fig. 2, but showing the switch rotor positionedfor circuit breaking movement and restrained 1n circuit making pos1-lost motion tooth engagement concerned in the detent tripping operation.

Fig. 8 illustrates a modification of the tripping mechanism.

Fig. 9 is a front elevation of the structure in Fig. 8 showing certainparts sectioned on plane 99 of that figure.

Fig. 10 shows a further modified form of tripping mechanism.

In the drawings, a single part when appearing in more than one view isdesignated by the same reference numeral;

In general construction the socket switch structure incorporating myimproved detent tripping mechanism is of the usual form comprisingwithin an outer casing 9 and retaining cap 10, two bracket-connectedupper and lower blocks 11 and 1.2 respectively between which is mountedthe switch mechanism, and from the lower of which blocks depends thethreaded receptacle 13 for an incandescentlamp 14-, two of theblock-connecting brackets having binding post screws 16, 16 toaccommodate the socket leadwires 17, 17.

The switch mechanism includes a centrally plvoted, axially slidable,conductive plate rotor-20, having oppositely disposed contact-wipingarms 21 suitably formed to ride over stationary, inclined contact plates22 for controlling the lamp circuit. The rotor 20 is rotated in stagesand at each full increment of rotor movement the arms 21, 21 areadvanced progressively overone of two pairs of diametrically oppositeinclined steps, one of said pairs comprising the blank steps 25, 25 andthe other of said pairs comprislng the steps 26, 26 which carryrespectively the contact plates 22, 22, above mentioned.

The rotor 20 is advanced by successive forward strokes of an oscillatoryactuator 30, axially slidable with the" rotor on the common pivot post29, through the one-way driving engagement of pawl teeth 31 on saidactuator with corresponding ratchet teeth 32 on said rotor,--suchengagement being established by the coiled spring 33, which exerts axialtension pressing the actuator against the rotor and the rotor againstthe incline steps and which also exerts torsional tension on theactuator operative after a driving stroke thereof to return it to thebeginning of its stroke, or positioned against ing shoulders 36,terminating each of the incline steps 25 and 26 serve as stationaryratchet teeth to prevent return of the rotor f plate 20 with theactuator 30 after a full driving stroke of the latter.

The relative position of the actuator stops 3 1 and 35 and of the stepshoulders 36 is such that a full driving stroke of the actuator advancesthe plate arms 21 fully over the shoulders which terminate the steps 25,25 after which the actuator will obviously be returned by spring 33 andin its lowest rotative plane to such an extent that the pawl teeth 31retreat to a position for engagement with the next succeeding ratchetteeth 32 respectively and in my present improvement I so position thestop 34: that on each return of the actuator'the extent of its retreatis sufiicient to provide an appreciably lost motion or back-lash in thetooth-engaging relation such as shown at 37 in Fig. 7. The purpose ofthis back lash is, to permit in one position of the parts, a repetitionof the initial part of the actuator driving stroke, before drivingengagement occurs between the pawl and ratchet teeth 31, and 32,-thisrepeated movement being utilized for tripping a detent in a manner andfor a purpose later to be described.

The position of the shoulders 36 that in spring 33 tends to cause saidarms 21 to slide rotatively forward, and to be dis charged from contactplates 22 onto the succeeding blank steps 25, 25, to break the circuitthrough the lamp. Before such discharge takes place, however, therotative advance'of the rotor 20 is positively arrested by engagement ofa projecting spur 44 on the edge of the rotor 20 (of which there are twoon diametrically opposite sides of the rotor) with a detent hook 40,pivoted to swing on a stud 41 mounted on the insulating block 12. -Atthis time the plate rotor 20 and its arms are positioned as shown infull lines in Fig. 3.

The electric circuit connections and contact arrangement are such thatadvance of the rotor 20 to its position shown in Fig. 3 electricallyenergizes a normally de-energized resistance wire 45-that is wound aboutand in heating relation to a bi-metallic thermostat 46 anchored at oneend to the bracket 47, so that heat begins to be delivered to saidthermostat and after a designed interval of time required to raise thethermostat to a certain temperature (which time may conveniently be fromone to two minutes) a straightening, or outbending, of the thermostatoccurs suflicient to retract the detent hook from restraining engagementwith spur 44 as shown in Fig. 5. The spring 33 then acts to dischargethe rotor as above described automatically to extinguish the lamp. IWhen so discharged, the rotor-spur 44 drops to a lower plane than theintercepting end of hook 40, so that said hook does not become againoperative to prevent further advance of the same spur when thethermostat cools.

It may be desired, however, to cause circuit-breaking movement of theswitch rotor 20 independently of this thermostaticallycaused detentrelease which depends for operation on action of the electric current.Especially is this true of the types of pull socket switches disclosedin my co-pending applications, Serial No. 422,750, filed Nov. 8, 1920,and Serial N 0. 421,554 filed Nov. 3, 1920, to which types of switchesmy present improvement is equally adaptable. Among other accomplishmentsthe present invention specifically provides an improved means to thisend, in a form of mechanism whereby the detent hook 40 may bemechanically and directly tripped by a partial forward stroke on theactuator after its return from the forward or driving stroke that placesthe rotor under control of the thermostatically operated detent hook 40.

In the present embodiment of my invention a tripping extension for saiddetent hook is provided, preferably in the form of a light leaf spring50, that may be riveted or otherwise secured to the hook 40 andextending therefrom inwardly in substantially tangential relation to thecircular path of a peripheral edge of the actuator 30. This actuator, ascommonly constructed, comprises a relatively thick segmentary plate 51made of fibre, or other suitable insulating material, secured to theunder surface of which is a relatively thin, punched-metal piece 52formed to serve as a hub for the actuator,

and from which piece the pawl teeth 31 are struck downwardly. The plate51 also carries spaced radially outwardly from the hub piece 52, apunched-metal channel-guide anchorage 53 for the pull chain 55. Theperipheral edge of the actuator above referred to may comprise merelythe edge of the relatively thick fibre plate, whichv as herein shown, isformed with a radially outwardly extending spur formation 56.

It will be clear that the normal travel of the spur formation 56, duringa normal driving stroke of the actuator, is normally in a helical pathrelative to the axis of oscillation of the actuator, because of themounting ping extension 50 is axially removed from the said helical pathit is clearly shown in Figs. 2 and 5 that the end of said extension isnormally positioned within the circular radial extent of said path, sothat engagement of said extension with said spur will occur if theactuator 20 is maintained substantially in its highest plane when it isreturned to the beginning of its driving stroke. When the rotor 20 isarrested in its position as shown in Fig. 3, however, it is evident thatthe actuator will be maintained in its highest plane, as shown in thatfigure, so that on return of the actuator after the driving stroke thatso positions said rotor, the spring leaf tripping extension 50 willyield radially outwardly to permit the passage of the spur 56 near theend of the return actuator stroke, immediately snapping back into thepath of said spur after the passage of the latter, so that at thebeginning of a subsequent forward stroke of the actuator,

the spur is operative to trip the detent 40 through longitudinal thruston the extension 50, and before driving engagement occurs between teeth31 and 32, because of the backlashshown in Fig. 7 and heretoforedescribed.

This tripping of the detent releases the rotor for its spring causeddischarge from the contact plates 22 exactly as in the case ofthermostatic retraction of the detent; and the rotor spur 44 and theactuator spur 56 both drop instantly to their lowest plane, as indicatedby the positions 44*, and 56*, respectively, in Fig. 4, whereby therotative parts are free for further advance circuitcontrolling movement.

.Tn Fig. 5 the broken line position of the resilient detent extension 50shows the change in position of this extension relative tothe path ofthe actuator spur 56 when the thermostat is heated. It will beunderstood from reference to this figure and to Fig. 4, that such changein position of the extension 50 constitutes ingeneral a movementradially inwardly toward the actuator pivot 29 anch rises to a higherplane. Such interference would be of a nature to cramp and distort theresilient extension 50, as the actuator spur would be beneath andoperative to force the extension upwardly edgewise. To prevent suchcondition the extension 50 is formed with a cam ear 57 at the bottomedge of its free end, and a co-operative bevel is formed at 58 on theupper peripheral edge of the actuator fibre plate 51, in the vicinity ofthe spur 56,-this cam ear and. bevel co-acting to cause a natural andunstrained yielding of the extension 50 in its designed direction offiexure away from the path of the actuator,

to prevent possible injury to the extension 50, if the switch isactuated before the thermostat has become cool. The nature of theimpingement that under these conditions might occur between the bevellededge of 58 of the actuator and the cam car 57 is clearly shown in Fig.6.

It will be appreciated that the arrangement described above utilizes anatural condition of relative and absolute actuator movement alreadyinherent in the well known type of pull socket switch for producing apermutation detent tripping function that provides for the operator theability by successive manual strokes on the actuator pull chain toconveniently and selectively establish the switch in any of its designedoperating positions, without delay or con straint, and requiring nospecial or unusual method of chain-manipulation.

Specifically, the operative effects that are available by the operatorin a socket switch embodying my improved detent trip-ping mechanism arethe ability by successive actuations of the usual pull chain first,-tolight the lamp by one full stroke of said chain;

second, when through with the light to actuate the switch by asubsequent pull chain stroke for automatically eifecting delayed lampextinguishment; third, to cause immediat and undela-yed extinguishmentof the lamp, if desired, by repeating the initial part of the lastmentioned stroke; or as an alternative to this last mentioned operation,a repetition of the full chain stroke that actuates the switch to effectdelayed automatic lamp extinguishment, may be made, which willmomentarily extinguish the lamp, but immediately reestablish it innormally lighted condition, for continuous use.

I have thus provided a pull socket switch free from undesirablemechanical features, either as to complication or delicacy, and a switchthat is manually governable by a single pull chain to light andextinguish a lamp as usual, but also containing means, operative whendesired, to delay the circuit breaking action of the switch.

It is to be understood that the mechanical principles underlying myinvention do not hmit its embodiment to the exact or even substantialform heretofore described. For instance, as shown in Fig. 8, I may mounta resilient tripping extension on the. actuator fibre. plate 51 andarrange the same for yielding flexure, not in a radial plane relative tothe axis of the actuator pivot, but in'a plane substantially parallal tosaid axis. In thls case, I may employ a rigid projection 61 extendingfrom the detent hook 40 to a position for being tripped by saidextension 60 according to the operative principles of my inventionheretofore described.

In Fig. 10, a modification is shown wherein provision is made forvarying the nature of displacement of the tripping extension when thethermostat moves to its heated position as shown in Fig. 5. Here thetripping extension appears as a rigid strut arm 62 pivoted at 63 andhaving a stop limiting spur 64. The strut arm 62 is yieldinglymaintained in its normal full line position by a light leaf spring 65that may conveniently be anchored in a slot in the top of hook pivotstud 41 so that the strut may move back as required to some suchposition as is shown in dotted lines in Fig. 10 when engaged by theactuator in its return movement. A projecting bracket 66 also extendsfrom this stud and has a turned down extremity 67 engaging with thetripping arm 62 to limit the movement of the same toward the center ofthe switch structure,the operative effect of said constraint being toprevent interference-causing displacement of the trippingextension 62,such as shown in Fig. 5. Obviously a constraining bracket such as 66could be employed with the type of tripping extension shown in F igs. lto 6 inclusive, in place of said cam ear and bevel formations. Y

The features of the improvement residing in the thermostatic controlmechanism 40, 41, 46 etc. and .co-operative switch contacts 21, 22, 38'etc. per se, are not claimed in this application but are the subjectmatter of claims in my co-pending application Serial No. 421,556, filedNovember 3, 1920.

The pull socket structure herein disclosed is of the simple type forsupporting and governing a single incandescent lamp, the cooperativeswitch circuits terminating in rotor-bridged contact plates carried ontwo of only four detent step formations. The switch may however havemore steps and more contact plates for governing additional circuitssuch as for a second switch-goveined lamp or dimming device for theusual lamp. There would clearly be no definite sequence of operation towhich such multiple switch arrangement would be restricted, such sequence depending entirely on the consecutive arrangement of steps andthe thermo-detent tripping device herein disclosed could be appliedequally well to any step.

Numerous other possible variations in form and arrangement of detailswill suggest themselves to a mechanic and obvious ly the novelmechanical principles involved. in my present invention are adaptable totypes of apparatus other than socket switches.

I do not, therefore, limit the scope of my 'by a forward stroke of saidelement to tension said device for forward automaticcircuit-governingimovement; a detent normally arranged to prevent saidmovement; and tripping mechanism for releasing said controller fromrestraint by said detent, operatively actuable directly by a repetitionof said forward stroke of said element,

2. An electric switch having in combination, relatively movablecontacts; an oscillatory actuator with a limited stroke, including aspring automatically to restore it to a normal position, and arranged byfull strokes alternately to close the switch and to place it undercontrol of automatic electric devices adapted to cause its delayedopenin said devices, including a detent normal y adapted to preventopening of the switch; and means co-operative between said actuator anddetent, when said switch is placed under control of said devices andwhen .iaid actuator is then returned to its normal position, adapted torelease said detent by further movement of said actuator.

3. Permutation switch mechanism embodying in combination, an oscillatorydrivin element having a limited stroke; and a riven switch circuitcontroller, both adjacently rotatable and axially slidable upon a commonpivot, said element and controller being maintained in pawl-and-ratchetdriving engagement by tension exerted axially on said element; acontact-carrying step disposed in the path of said controller to opposesaid tension and formed to resent a riding surface thereto inclinedobliquely to the plane of controller rotation, whereby mounting of saidstep by said controller causes said element to rise from a lower planeat the beginning of its driving stroke to a higher plane at the end ofsaid stroke; detent means operative to retain said controller nearthetop of said step, whereby said element is then retained in said higlierplane, during its return stroke; and tripping mechanism for said detentmeans positioned to be operatively engaged by said element only when thelatter is near the beginning of its driving stroke and in said higherplane, whereby a subsequent forward stroke of said element actuates saidmechanism to release said controller from restraint by said detentmeans.

4. In a pull socket switch for an incandescent lamp', the combinationwith a movable switch circuit-controller progressively movable to lightand extinguish the lamp by successive strokes of a manually-operablespring-returned actuator, of detent means operatively related to saidcontroller and electrically governed thereby automatically to delay thelamp-extinguishing movement of said rotor a substantial period of timeafter the stroke of said actuator adapted to cause said action; andmeans whereby the repetition of said actuator stroke renders inoperativesaid detent means, thereby to cause immediate lamp extinguishment.

5. A pull socket switch having a step-bystep, rotatable, double-ended,conductive, current-switching member; circularly disposed stationarycontacts arranged to be engaged by the ends of said member, inclinedalong the axis of rotation of said member toward said member, andmounted on insulating formations constituting teeth to prevent movementof said member in one direction, the terminal portion of said contactsbeing oppositely inclined; an oscillatory actuator arranged, relativelyto said member,

' oppositely to said contacts, concentrically pivoted with said member,having pawl-andratchet engagement therewith, and further having astop-limited stroke; a coiled spring arranged co-axially of the commonpivot of said member and actuator and to exert axial pressure andtorsional stress on said actuator; electrical means, including a detent,arranged to hold said member in electrical contact on said terminalportion and then to release said member; and tripping means for saiddetent arranged to be energized by said actuator only when the latter isreturned rotatively to its normal position and is axiall displaced byretention of sai member y said detent.

6. In a pull socket switch, embodyingl a circuit-controlling rotor;pawland-ratc et actuating mechanism therefor including a awl devicehaving a limited forward stroke or rotatively advancin said rotor overangular contact carrying onnations circularly arranged in the path ofsald rotor to prevent backward movement of the latter, and furtherembodying common resilient means for rotatively returning said devicethe beginning of its stroke and for maintammg operative engagement ofsaid device w th said rotor and thereby of said rotor with saidformations, in combination; a stationary contact formationco-operatlvely arranged with an engaging portion of said rotor, in oneposition thereof, so that the thrust of said resilient means opposesbackward movement of said rotor, and tends to discharge said rotorrotatively forwardly from said formation to break the circuit; a detentnormally positioned to arrest forward movement of said rotor from itssaid position; and tripping means arranged to be operatively actuated bysaid device only upon a repeated forward stroke of said devicesubsequent to the establishment of said rotor in its said position.

7. In a pull socket switch embodying a circuit-controlling rotor;pawl-and-ratchet actuating mechanism therefor including a pawl devicehaving a limited stroke for rotatively advancing said rotor over angularcontact-carrying tooth-formations circularly arranged in the path ofsaid rotor to prevent backward movement of the latter; and resilientmeans for rotatively returning said device after its stroke and formaintaining operative engagement of said device with said rotor and ofsaid rotor with said formations, in combination; a co-operative detentarrangement operative to arrest both advance and backward movement ofsaid rotor when the latter is established in a certain circuit makingposition by one advance stroke of said device; resilient means energizedby said stroke of said device and tendmg to advance said rotor from 1tssaid position to break the circuit; and mechanism for tripping saiddetent arrangement to release said rotor, o erable by said device onlyupon a repeated orward stroke of said device subsequent to theestablishment of said rotor in its said position.

8. In anelectric switch, including manually actuable mechanism fortripping a switch governing detent that is normally movable between aninterceptive and a retractive position by automatically-acting meanselectrically governed through said switch, the combination, with saiddetent, of a pivoted oscillatory switch actuator normally constrainedfor limited advance and return strokes in a normal helical path relativeto its pivotal axis; means to constrain the rotative oscillations ofsaid actuator to substantially a single plane when said switch isundercontrol of said detent and auto- -matically-acting means; a resilienttripping further arranged when said detent occupies.

its said" retracted position to lie in said helical path; said extensionbeing co-operatively positioned and formed with an engaging port-ion ofsaid actuator to permit the rotative return stroke of said actuator insaid plane, and to be engaged positively thereby to trip said detentupon the subsequent advance stroke of said actuator, together with aco-operative cam formation on said detent extension and on said actuatorarranged to cause normal yielding displacement of said resilientextension from the helical path of said actuator to permit the passageof the latter when said detent occupies its said retracted position.

9. In an electric switch, including-manually actuable mechanism fortripping a switch governing detent, the combination, with said detent,of a pivoted oscillatory switch actuator normally constrained forlimited advance and return strokes in a normal helical path relative toits pivotal axis; means to constrain the rotative oscillations of saidactuator to substantially a single plane when said switch is undercontrol of said detent, a resilient trippingvextension carried by saiddetent in said plane and arranged to lie within the radial extent ofsaid helical path but axially removed from said path; said extensionbeing co-operatively positioned and formed with an engaging portion ofsaid actuator to permit the rotative return stroke of said actuator insaid plane, and to be engaged positively thereby to trip said detentupon the subsequent advance stroke of said actuator.

10. A detent and detent-tripping arrangement, embodying an oscillatorydrive mem her having a limited stroke; a driven element; means includingan element-engaging detent to detain said element after a full drivingstroke of said member and further then to tension said element forautomatic further movement and comprising instrumentalities adapted tocause such movement, said element,-member, and means being cooperativelyarranged so that said member,

during its return stroke, is maintained in a different plane of rotationthan that occupied by it after such further movement of said element;and a cooperative tooth formation on said member and resilient finger onsaid detent arranged to engage when said member is in said differentplane, and then topermit escape of said member on its said returnstroke, but then to release said detent from said element on a forwardmovement of said member.

11. A detent and detent-tripping arrangement, embodying an oscillatorydrive member having a limited stroke; a driven element; means includingan element-engaging detent to detain said element after a full drivingstroke of said member and further then to tension said element forautomatic further movement and comprising instrumentalities adapted tocause such movement, said element, member, and means being cooperativelyarranged so that said member, during its return stroke, is maintained ina different plane of rotation than that 00- cupied by it after suchfurther movement of said element; and a cooperative tooth formation onsaid member and resilient finger on said detent arranged to engage whensaid member is in said different plane, and then to permit escape ofsaid member on its said return stroke, but then to release said detentfrom said element on a forward movement of said member; said member andextension carried by said finger being also co-opera-' tively formed andpositioned to cause escapement of said finger from said member on aforward stroke of the latter in the plane occupied by it after saidfurther movement of said element.

12. In a pull socket switch adapted to be operated by successiveactuations of a controlling pull chain, and incorporating agenciesautomatically operative to delay circuit breaking movement of theswitch, means whereby successive actuations of said pull chainrespectively make the circuit, establish the switch under control ofsaid agencies and then move the switch directly to break the circuit.

13. In a pull chain operated socket switch, the combination of automaticmechanism arranged to cause self-delayed circuit-breaking movement ofthe switch, instrumentalities whereby one actuation of the pull chainenergizes said mechanism, and means whereby a subsequent actuation ofthe pull chain operates the switch directly to break the circuit.

14. A switch for an electric circuit having contacts, a contactcontrolling member movable by successive movements to make and break thecircuit, slow action controlling instrumentalitiesto delay the circuitchanging elfect of the movement of said member 'for a substantialinterval of time, and means whereby subsequent movement of said memberestablishes the circuit change irrespective of the action of saidintrumentalities.

15. A switch for an electric circuit having contacts, a contactcontrolling member means to move the same for effecting a circuitchange, slow action controlling means to delay the circuit changingeffect of said member for a substantial interval to time after movementthereof, and means operative through subsequent movement of said memberunretardedly to produce said circuit change.

16. A switch for an electric circuit having contacts, a contactcontrolling member movable by successive movements to make and break thecircuit, slow action controlling instrumentalities to delay the breakingof said circuit for a substantial interval of time, and means wherebysubsequent movement of said member may'break said circuit immediatelyirrespective of the control by said instrumentalities.

17. A switch for an electric circuit having contacts, a contactcontrolling member movable by successive movements to make and break thecircuit, a thermo-electric control device todelay the current changingeffect of a movement of said member for a substantial interval of timeafter said movement, and means whereby subsequent movement of saidmember establishes said current changing efi'ect irrespective of thecontrol of said instrumentalities.

18. A switch for an electric circuit having contacts, a contactcontrolling member movable by successivemove-ments to make and break.the circuit, a thermo-electrically controlled detent to delay thecurrent changing efiectof a movement of said member for a substantialinterval of time after said movement, and means whereby subsequentmovement of said member withdraws said detent.

19. A pull socket switch for an incandescent lamp having contacts, anactuator, successive actuations of which make and break the lampcircuit, a thermo-electrically controlled detent to delay the breakingof the circuit, and means whereby a subsequent movement of the actuatorwithdraws the detentpermitting immediate breaking of the circuit.

20. A socket switch for an incandescent lamp having an oscillatoryactuator, a rotary contact controller adapted to be advancedprogressively step by step by successive movements of the actuator tomake and break the lamp circuit, athermoelectric control device to delaythe breaking of the circuit for a substantial interval of time, andmeans whereby a subsequent movement of the actuator serves to break thecircuit irrespective of the control device.

21. A socket switch for an incandescent lamp having an oscillatoractuator, a rotary contact controller a apted to be advancedprogressively step by step by successive movements of the actuator tomake and break the lamp circuit, a thermo-electrically controlled detentto delay the completion of the circuit breaking movement of thecontroller for a substantial interval of time following the circuitbreaking movement of said actuator, and. a detent' release mechanismadapted to be actuated by a subsequent movement of the actuator to causeimmediate breaking of the circuit when desired.

22. A switch for an electric circuit having a movable circuit controlmember adapted to make and break the circuit, means to impart movementthereto to produce a given circuit changin efiect, adetent to arrest themovement 0 the same toretard the said and break the lamp circuit, adetent to arrest movement-of the same to retard the circuit breakingmovement of said member, a thermo-electric control device for thedetent, a supplemental detent control movable independently of both thecontrol member and the thermo-electric control device to independentlywithdraw the detent, and a manually operable actuator for saidsupplemental detent control.

24. 'A switch for an electric circuit having a movable circuit controlmember adapted to inakeand break the circuit, a slow acting controldevice combined with means to retard the circuit changing movement ofsaid 'member for a substantial interval of time,

means movable independently of said memher and device for independentlyactuating said means to cause unretarded circuit changing movement, andactuating means for said independently movable means.

25. A socket switch for an incandescent lamp having a movable circuitcontrol member adapted to make and break the lamp circuit, a manuallyoperable actuator adapted to move said member ,for lighting andextinguishing the lamp, a detent operatively related to said member,electrically governed means to control the detent to delay the lampextinguishment for a substantial period of time after t-helampextinguishing movement of the actuator, and means to move the detent bya repetition of the actuator movement to cause immediate lampextinguishment.

26. A socket switch for an incandescent lamp having an actuator adaptedto operate the switch, and incorporating agencies automaticallyoperative to retard lamp extinguishment for a substantial period of timefollowing a lamp extinguishing movement of the actuator, and having alsomeans to produce, an unretarded extinguishment of the lamp through asubsequent actuation of the actuating device.

Signed at Boston, in the county of Suffolk ahd Commonwealth ofMassachusetts, this 5th day of November, 1920.

RAYMOND B. SMITH.

